Colorectal Cancer:
Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality, responsible for an estimated half a million deaths per year, mostly in Western, well developed countries. In these territories, CRC is the third most common malignancy (estimated number of new cases per annum in USA and EU is approximately 350,000 per year). Estimated healthcare costs related to treatment for colorectal cancer in the United States are more than $8 billion.
Colorectal Cancer Diagnosis:
Today, the fecal occult blood test and colonoscopy, a highly invasive procedure, are the most frequently used screening and diagnostic methods for colorectal cancer.
Other diagnostic tools include Flexible Sigmoidoscopy (allowing the observation of only about half of the colon) and Double Contrast Barium Enema (DCBE, to obtain X-ray images).
Colorectal Cancer Staging:
CRC has four distinct stages: patients with stage I disease, have a five-year survival rate of >90%, while those with metastatic stage IV disease have a <5% survival rate according to the US National Institutes of Health (NIH).
Colorectal Cancer Treatment:
Once CRC has been diagnosed, the correct treatment needs to be selected. Surgery is usually the main treatment for rectal cancer, although radiation and chemotherapy will often be given before surgery. Possible side effects of surgery include bleeding from the surgery, deep vein thrombosis, and damage to nearby organs during the operation.
Currently, 60 percent of colorectal cancer patients receive chemotherapy to treat their disease; however, this form of treatment only benefits a few percent of the population, while carrying with it high risks of toxicity, thus demonstrating a need to better define the patient selection criteria.
Colorectal cancer has a 30 to 40 percent recurrence rate within an average of 18 months after primary diagnosis. As with all cancers, the earlier it is detected the more likely it can be cured, especially as pathologists have recognised that the majority of CRC tumours develop in a series of well-defined stages from benign adenomas.
Colon Cancer Survival by Stage
StageSurvival RateI93%IIA85%IIB72%IIIA83%IIIB64%IIIC44%IV 8%Therapeutic Challenges
The major challenges in colorectal cancer treatment are to improve early detection rates, to find new non-invasive markers that can be used to follow disease progression and identify relapse, and to find improved and less toxic therapies, especially for more advanced disease where 5 year survival is still very poor. There is a great need to identify targets which are more specific to the cancer cells, e.g. ones which are expressed on the surface of the tumour cells so that they can be attacked by promising new approaches like immunotherapeutics and targeted toxins.